The present invention relates in general to combination locks, and more particularly to time delay combination locks of the tumbler wheel type having a timing mechanism therein interrelated with the tumbler wheel and drive cam pack to effect retraction of the bolt a selected time delay period following adjustment of the tumblers in accordance with the proper dial combination.
The present invention is directed to an improved time lock for protecting safes, vaults and other enclosures which incorporate a plurality of tumblers, a driving cam spindle connected to a dial, and associated components typical of tumbler wheel type combination locks, together with a timing mechanism and interconnections for delaying the time at which the safe door can be opened after successful operation of the combination, thereby discouraging daylight holdups. Heretofore, a number of such time delay combination lock mechanisms have been produced, many of which were of the type disclosed in earlier U.S. Pat. Nos. 1,867,001 and 2,079,702 to Diesel and 2,035,526 to Brown, all assigned to the assignee of the present invention. Each of these involves a plurality of tumbler wheels, a driving cam and spindle connection from the driving cam to an operating dial, and lost-motion driving connections, together with a timing mechanism which was provided with means for preventing the usual fence lever pivoted to the bolt from dropping to the unlocking position for retraction of the bolt until a preset time delay period following dialing of the proper combination.
More recently, similar time delay combination locks have been produced commercially, involving one timer unit, or a pair of tandem operating timer units together with a blocking lever in the opening path of the fence lever which is under such control of the timer unit that the blocking lever is positioned to prevent retraction of the bolt until the time delay period has timed out. These prior time delay locks usually required complete removal of the timing mechanism from the lock casing in order to effect a change in the combination of the lock. Additionally, such locks encountered problems when forced entry was attempted because the timing movement was the source of the restraining force tending to hold the blocking lever against being forced to unlocking position and therefore the timing movement had to suffer the abuse of the forced entry attempt.
An object of the present invention is the provision of a novel time delay lock of the tumbler wheel combination lock type, wherein the mechanism is arranged in such a manner that the change key can be introduced into the lock case through the timing mechanism or timing movement to change the combination, without requiring removal of the timing mechanism from the lock case to effect combination change.
Another object of the present invention is the provision of a novel time delay combination lock of the plural tumbler wheel type, wherein the timer controlled blocking lever for restraining the lock against opening following dialing of the proper combination until the delay period has timed out is in supported abutment with integral shoulder formations on the lock case or housing, facilitating resistance to forced entry attack on the lock by providing lock casing support against forced dislodgment of the blocking lever.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.